Replaceable dilatation catheter

ABSTRACT

A balloon dilatation catheter comprises a flexible, tubular catheter shaft which carries a dilatation balloon adjacent the distal end. The catheter shaft defines an inflation lumen communicating with the balloon and a guidewire lumen extending at least most of the length of the catheter and extending through the catheter distal end. A longitudinal slit is defined in the catheter shaft between the guidewire lumen and the catheter exterior. This slit longitudinally extends along the majority of the catheter length from a position proximal of the balloon to a position that is at least adjacent the catheter proximal end.

This is a division of application Ser. No. 07/713,430, filed Jun. 10,1991, now U.S. Pat. No. 5,205,822.

BACKGROUND OF THE INVENTION

Dilatation catheters are used in particular for dilating arteriallesions or stenoses in the coronary arteries, when such stenosesthreaten to seriously obstruct the flow of blood through the artery.Typically, dilatation catheters are emplaced in the coronary arterystenosis by advancing a guidewire which carries a catheter into thecoronary artery, and first advancing the guidewire through theconstricted aperture at the stenosis. Then, the dilatation catheter,threaded about the guidewire, is advanced therealong until the balloonof the catheter is positioned within the proper area of the coronaryartery, after which the balloon is inflated to dilate the artery wall.

In Bonzel U.S. Pat. No. 4,762,129 a dilatation catheter is disclosed inwhich the guidewire along which the catheter is advanced is retained ina catheter lumen only at an area near the distal end of the catheter,typically being surrounded by the balloon. Along the rest of thecatheter length, the guidewire is free and unconnected to the catheter.

An advantage of this is found in the situation when it becomes necessaryto remove the catheter without removing the guidewire. With conventional"over the wire" catheters, it is often necessary in this circumstance toinstall a guidewire extension on the proximal end of the guidewire priorto withdrawing the catheter, so that the guidewire can at all times begripped and held in stationary position as the catheter is beingwithdrawn, to avoid the accidental, partial withdrawal of the guidewirealong with the catheter. This is of course undesirable since the distaltip of the guidewire may then be pulled out of the constricted stenosisarea of the coronary artery, and thus would require repositioning.

While the guidewire extensions described above are in regular clinicaluse, they are quite inconvenient since they may have to be four feetlong or so, extending and coiling all over the operating room in aninconvenient manner.

With the catheter of the Bonzel patent, the use of a catheter extensionmay be dispensed with, since the guidewire may be gripped by the surgeonat a position which is lateral to the catheter as the catheter is beingwithdrawn, since the guidewire is not enclosed in a catheter lumen alongmost of the length of the catheter. Thus, the catheter can be withdrawnwhile the guidewire is held in its desired position so that it is notaccidentally withdrawn along with the catheter.

Horzewski, et al. U.S. Pat. No. 4,748,982 shows another design ofdilatation catheter which can be withdrawn from the patient whileleaving the guidewire in a desired position within the patient, withoutthe need for a long guidewire extension. Here also, a large portion ofthe guidewire is positioned laterally of the catheter rather than withina catheter lumen, so that the catheter may be withdrawn while theguidewire is manually gripped and retained in place. Also, the guidewirecan pass through a longitudinal slot 36 defined in the catheter of theHorzewski, et al. patent, as described therein.

Both of the catheters disclosed in the patents cited above exhibitsignificant clinical disadvantages. For example, conventional,over-the-wire dilatation catheters, where the guidewire occupies acatheter lumen throughout most of its length, are better subject tocontrol of the catheter as it is advanced into the arterial system ofthe patient. Difficulties are encountered in the tracking of catheterswhich lack a guidewire passing through the great majority of its length.This complicates and renders more difficult the basic advancementtechnique of such catheters to their desired point of use within thearterial system of the patient. Generally, dilatation catheters havingshort guidewire-containing lumens relative to their overall length needto carry some other form of stiffener, such as a metal rod or tube, inorder to obtain the minimum standards of trackability and pushability.This adds to the complexity and cost of the catheter structure.

Also, in some clinical situations there may be a need to replace theguidewire rather than the catheter after both have been emplaced. Thisis very difficult to accomplish with the catheters of the two citedpatents.

Accordingly, there is a clinical need for a dilatation catheter whichexhibits the advantages of the catheters of the cited patents, but whichalso exhibits the advantages of conventional, over-the-wire catheters,in that they should be easily controllable due to the presence of theguidewire along most or all of the length thereof, with the desiredcatheter not requiring a stiff, reinforcing rod or tube as part of thecatheter itself. Such a catheter needs to have excellent trackabilityand pushability, while at the same time it can be replaced without theneed of a long, cumbersome catheter extension attached to the distal endof the guidewire.

Also, there is a need for a catheter exhibiting all of these advantages,in which, after emplacement of the catheter, the guidewire can be easilyreplaced rather than the catheter, if that is desired, but the cathetercan also be easily replaced when that is desired.

By this invention, a catheter exhibiting the above advantages isprovided. The catheter of this invention is very effective both inclinical utility and flexibility, while remaining of low cost and simpleconstruction.

DESCRIPTION OF THE INVENTION

By this invention, a balloon dilatation catheter is provided havingproximal and distal ends, with a flexible, tubular catheter shaft whichcarries a dilatation balloon adjacent the distal end. The catheter shaftdefines an inflation lumen which communicates with the balloon, plus aguidewire lumen extending at least substantially the entire length ofthe catheter and extending through the catheter distal end.

A longitudinal slit is defined in the catheter shaft between theguidewire lumen and the catheter exterior. This slit extendslongitudinally along the majority of the catheter length from a positionproximal of the balloon to a position that is at least adjacent thecatheter proximal end.

Alternatively, the catheter slit may be replaced with an equivalent lineof tearing weakness, which may be easily converted into a slit by anobject passing therealong, as described in greater detail below.

Preferably, the guidewire lumen is open from the catheter distal end toa position at least adjacent to the proximal end. Typically, theguidewire lumen is open from end to end of the catheter and through theproximal and distal ends. However, if desired, the guidewire lumen maybe closed off adjacent the proximal catheter end, and a side aperturemay be defined between the guidewire lumen and the catheter exterioradjacent the proximal end. In this circumstance, the slot or line ofweakness described above communicates with the side aperture, whichaperture serves as an exit port for the guidewire from the guidewirelumen.

Preferably, the catheter of this invention carries a substantially rigidhub at the catheter proximal end. The hub defines a conduit connectingwith the guidewire lumen, with the slit of the catheter body describedabove extending to the hub. A longitudinal slot extends the length ofthe hub in communication between the hub conduit and the hub exterior.This slot is also aligned with the slit, to permit a sliding member inthe slot to slide into the slit, as described below.

Additionally, the hub typically contains a second conduit whichcommunicates with the proximal end of the inflation lumen in thecatheter shaft.

Thus, to install the catheter of this invention while holding aguidewire emplaced in the patient in its desired position, one cansimply grip the end of the guidewire, typically within the catheter witha tool which fits in the catheter guidewire lumen and carries atransverse handle that can project out of the slit of the catheter, orthe line of tearing weakness which has been converted into a slit by thepassage of the transverse handle. Thus, the catheter can be installedwhile gripping the transverse handle, retaining it and the guidewire towhich it attaches in a typically stationary position. The guidewiregripping tool with its angled handle is preferably inserted through theproximal end of the catheter, first through the preferred slot of thehub, and then being advanced along the slit into engagement with theguidewire. After such engagement, the catheter can be advanced asdesired as the guidewire is firmly retained in its desired position.

To remove the catheter of this invention from implantation about aguidewire within the patient, as one withdraws the catheter, theguidewire can be bent outwardly adjacent its proximal end to penetratelaterally through the slit of the catheter. Thus, the guidewire can beheld in stationary position as the catheter is withdrawn.

Alternatively, if the catheter carries a line of tearing weakness ratherthan an open slit, the above-described guidewire gripping tool may beattached to the proximal end of the guidewire, and the catheter may bewithdrawn as the lateral handle of the tool cuts the line of tearingweakness and projects laterally out through the resulting slit thusformed.

DESCRIPTION OF THE DRAWINGS

In the drawings, FIG. 1 is an elevational view of the catheter of thisinvention, showing the gripping tool within the guidewire lumen of thecatheter;

FIG. 2 is an elevational view of the catheter of FIG. 1, rotated 90degrees about its longitudinal axis;

FIG. 3 is a section taken along line 3--3 of FIG. 1;

FIG. 4 is a section taken along line 4--4 of FIG. 1;

FIG. 5 is a section taken along line 5--5 of FIG. 1;

FIG. 6 is an elevational view of the proximal end of the catheter ofFIG. 1;

FIG. 7 is a fragmentary, sectional view taken along line 7--7 of FIG. 6;

FIG. 8 is an enlarged, elevational view of the guidewire gripping toolwith its lateral handle, shown in gripping relation with the proximalend of a guidewire; and

FIG. 9 is a cross-section similar to FIG. 5 but showing a modifiedembodiment of the catheter of FIG. 1, having a line of tearing weaknessrather than a slit, which catheter is otherwise identical to that ofFIG. 1.

DESCRIPTION OF SPECIFIC EMBODIMENTS

Referring to the drawings, catheter 10 is disclosed, being of aconventional over-the-wire type, but having distinctions fromconventional catheters as described herein. Catheter 10 is specificallyfor angioplasty procedures such as PTCA, carrying an angioplasty balloon12 adjacent its distal end and a substantially rigid plastic hub 14 atits proximal end.

Flexible, tubular catheter shaft 16 may be made of conventionalmaterials, for example nylon or poly(ethylene terephthalate) having ashore D durometer of about 60-75, specifically about 72. As shown inFIGS. 4 and 5, catheter shaft 10 is made of extruded, double lumentubing, specifically with an inflation lumen 18 and a guidewire lumen20, such tubing being manufacturable in accordance with Fontirroche etal. U.S. patent application Ser. No. 532,626, filed Jun. 4, 1990 nowU.S. Pat. No. 5,063,018. Inflation lumen 18 communicates with theinterior of balloon 12, with a portion of catheter shaft 16 being cutaway to expose lumen 18 in communication with the tubular balloon 12,which is sealed at both ends to catheter shaft 16, all in a generallyconventional manner. Guidewire lumen 20, on the other hand, extendsthrough and is open to the distal end of catheter 10.

As also shown in FIGS. 6 and 7, hub 14 is an integral plastic memberthat defines a pair of conduits 22, 24. Hub 14 is conventionally sealedto the proximal end of catheter shaft 16, with conduit 22 communicatingwith inflation lumen 18 and conduit 24 communicating with guidewirelumen 20.

In accordance with this invention, catheter shaft 16 defines alongitudinal slit 28 in its wall, which slit is positioned betweenguidewire lumen 20 and the catheter exterior as particularly shown inFIG. 5, and which extends along the majority of the catheter length froma position 30 which is proximal of balloon 12 to a position that engagescatheter hub 14. As shown in FIG. 5, slit 28 is preferably anormally-closed slit.

Catheter hub 14, being typically made of substantially rigid plastic,defines an open slot 32, slot 32 being aligned with slit 28 to permit asliding member positioned in slot 32 to slide into slit 28.

Slit 28 typically is spaced a substantial distance from balloon 12 andthe distal end of catheter 10. For example, the spacing of distal end 30of slit 28 from the catheter distal tip may be at least 27 centimetersin an arterial catheter for angioplasty, which typically may have anoverall length on the order of 135 centimeters.

As shown in FIG. 8, a gripping tool 36 may be provided for engaging theproximal end of guidewire 34. The gripping mechanism of gripping tool 36may be basically similar to the CINCH™ guidewire extension device,currently on sale by the Cordis Corporation of Miami, Fla. A stiff wire38 defines a lateral loop or convolution 40 upon which there may bemounted a handle 42 made of plastic or the like, for example by insertmolding. The distal end of wire 38 carries a metal sleeve 44, with acoil spring of flat wire 46 being carried therein, and retained byappropriate crimps or dimples in the wall of tube 44. Spring 46 isproportioned so that when the tapered, proximal end 48 of guidewire 34is inserted into the cylindrical aperture of the coiled spring, theindividual coils of spring 46 are stretched outwardly to provide aspring retention thereof. Then, when retention member 36 is pulledrearwardly, the gripping tension of the coil spring 46 against guidewire34 is increased, rather in the manner of a "Chinese finger trap," sothat the end of guidewire 34 is firmly captured and retained therein fora firm connection.

When it is desired to disconnect gripping tool 36 from the guidewire 34,one only has to rotate tool 36 relative to the guidewire 34 in adirection to cause the coils of spring 46 to loosen and open, at whichpoint guidewire 34 is released.

A device incorporating the above principles for the gripping tool 36 isdisclosed in U.S. patent application Ser. No. 510,523, filed Apr. 18,1990 and entitled Guidewire Extension System, U.S. Pat. No. 5,113,872,except that the device illustrated therein does not have a laterallyextending wire convolution 40 nor a handle member 42.

The catheter of this invention may be normally used in the conventionalmanner of an angioplasty catheter, being inserted into the coronaryartery of a patient by following a guidewire to direct the catheterballoon 12 to a desired position for inflation of a stenotic portion ofan artery. The catheter and guidewire may be advanced together, with thedistal tip of the guidewire leading. Alternatively, the surgeon mayinsert the guidewire into the patient first, positioning its distal endin the stenosis as desired. Then, gripping tool 36 may be inserted intothe proximal end of catheter 10, with the side handle 40 thereofprojecting first outwardly through slot 32 of hub 14 as tool 36 isadvanced, and then advancing into the catheter shaft 16 where handle 40projects outwardly through slit 28. See FIG. 1.

Then, the proximal end of wire 34 is placed into the distal end ofcatheter 10, as also shown in FIG. 1. The wire and the catheter arebrought together with the catheter advancing along the wire, typicallywithout disturbing the position of the wire in the patient, until thewire 34 connects with tool 36 within the catheter, in the manner ofconnection illustrated in FIG. 8. Then, by gripping handle 42 of tool36, one can advance catheter 10 along the wire within the patient whileholding guidewire 34 in a reliably stationary position. Catheter 10 maythus be advanced until tool 36 exits once again the proximal end of thecatheter.

In some circumstances, it turns out that a particular catheter isunsuitable for the clinical situation in hand. In this case, anoriginally implanted catheter must be withdrawn, but at the same time itis important to cause the guidewire to retain its desired position whilethe catheter is being withdrawn. In the prior art, to accomplish this itwas necessary to attach a lengthy guidewire extension to the proximalend of the guidewire itself, so that a portion of the guidewireextension can be gripped to hold the guidewire in position while thecatheter is being withdrawn. Alternatively, when a catheter of theBonzel '129 or the Horzewski et al. '982 patents is in use a guidewireextension is not needed, but disadvantages of these structures asdiscussed above are encountered.

The catheter of this invention may be withdrawn from a position ofimplantation in the patient without using a guidewire extension.Instead, one can grip the proximal end of the guidewire and bend itlaterally so that the guidewire protrudes laterally outwardly firstthrough slot 32 of catheter hub 14, and thereafter through slit 28 ofcatheter body 16. Catheter 10 may be withdrawn from the patient whileone holds the laterally projecting portion of the guidewire stationary,while withdrawing the catheter so that the slit 28 thereof slides alongthe laterally bent portion of the guidewire as the catheter iswithdrawn.

Typically, about 50 cm. of the guidewire will project out of the patientwith the guidewire properly implanted. Thus, by the time the guidewirereaches the distal end 30 of slit 28, when of proper length the distalend of catheter 10 will have been removed from the patient, so that aportion of projecting guidewire distal to the catheter can be gripped,and the catheter can be taken off the proximal portion of the guidewirethat projects out from the patient.

Thus, the catheter of this invention may be withdrawn from its positionof implantation in the patient without using a guidewire extension.

Then, another catheter may be inserted on the guidewire in the mannerdescribed above.

Contrary to certain prior art, the catheter of this invention can bereliably advanced along a preimplanted guidewire to a position forexample where the balloon 12 occupies a stenosis site in the coronaryartery, without changing the guidewire position and without a guidewireextension, while maintaining the important characteristics of goodtrackability and pushability without the need for added stiffeningmembers carried on the catheter. Catheter 10 may be limp and softrelative to the guidewire, being stiffened and guided by guidewire 34within lumen 20.

Also, by this invention, the guidewire 34 may be removed from itsposition while the catheter 10 of this invention is retained inposition, by simply holding the catheter in place as the guidewire ispulled out. Thereafter, a fresh guidewire can be installed throughcatheter 10 to its desired position.

Typically, when a new guidewire is being advanced through catheter 10,it is desirably inserted through conduit 24 of hub 14 by means of ahollow, tubular needle member temporarily placed within conduit 24 tokeep the guidewire in a central position as it is advanced.

The catheter of this invention may be modified, if desired, as shown atFIG. 7, by inserting a plug or otherwise closing the proximal end ofguidewire lumen 20 as shown in dotted lines at reference numeral 46.Then, an optional side aperture 48 may be provided for the guidewire tobe removed. By this means, slot 32 of hub 14 may be eliminated, as wellas conduit 24.

Referring to FIG. 9, another modification of the catheter of thisinvention is shown, apart from which the modified catheter may beidentical to the catheter of FIG. 1. In this circumstance, slit 28 ofthe original catheter is modified to be a line of tearing weakness 28arather than a slit. Basically, line of tearing weakness 28a is like aslit except for a thin, connecting membrane of material which isrelatively easily broken. In this circumstance, it is often desireablefor the gripping tool 36 used to carry a cutting blade 50, shown indotted lines in FIG. 8, to assist in cutting the thin membrane of lineof weakness 28a as tool 36 is distally advanced along catheter 10. Thus,by such advancement, line of weakness 28a is turned into a slit similarto slit 28.

An advantage of the structure of FIG. 9 is that the catheter, whenoriginally installed along a guidewire in conventional manner, does nothave a slit through which weeping of blood or other fluid may takeplace. In many clinical angioplasty procedures it is not necessary toreplace the catheter, and a catheter similar to FIG. 9 will perform in amanner substantially similar to conventional over-the-wire catheters.However, in the event of the need of catheter replacement, such acatheter may exhibit the advantages of this invention.

When using a catheter of the embodiment of FIG. 9 and such a catheter10a is in an implanted relation in the patient with guidewire 34, theguidewire typically projects outwardly from the proximal end of hub 14(FIG. 1), through conduit 24. To remove the catheter from the patientwithout disturbing guidewire 34, and without using a guidewireextension, one may connect gripping tool 36 to the end of guidewire 34in the manner shown in FIG. 8. Then, by grasping handle 42 one can holdguidewire 34 with gentle retention as catheter 10 is withdrawn. Duringthe withdrawal process, convoluted wire portion 40 slides first throughslot 32 of hub 14, then engaging line of weakness 28a, cutting it withblade 50 and opening it up by the passage of convoluted wire portion 40as catheter 10 moves rearwardly. This causes tool 36 to move relativelydistally of the catheter, although it is the catheter that is moving,i.e., being withdrawn. By this means, guidewire 34 can be retained inits desired position as catheter 10 is withdrawn. When desired, tool 36may be rotated in the direction to loosen the coils of spring 46, sothat the tool 36 and the catheter can be removed from guidewire 34without disturbing its position.

Then, another catheter 10 or 10a may be applied to guidewire 34 forinstallation thereof in a manner previously described. The portion ofguidewire 34 that projects from the patient is typically much shorterthan the length of catheter 10. Thus, gripping tool 36 is inserted intoconduit 24 and then into guidewire lumen 20, as before, with theconvoluted wire loop 40 passing first through slot 32 and then alongslit 28 or line of weakness 28a as tool 36 is advanced. Catheter 10 maybe placed onto the proximal end of guidewire 34 and advanced until theproximal end of the guidewire engages tool 36 in the catheter, beingpositioned at least approximately as shown in FIGS. 1 and 2. When tool36 is firmly linked with the proximal end of guidewire 34, one can grasplateral handle 42 to hold guidewire 34 in its desired, implantedposition as catheter 10 or 10a is distally advanced along the guidewire.As this happens, tool 36 and guidewire proximal end 48 move relativelyproximally of the catheter, first along slit 28 and finally along slot32 and out of the proximal end of the catheter, as the catheter isimplanted into the patient.

The above has been offered for illustrative purposes only, and is notintended to limit the scope of the invention of this application, whichis as defined in the claims below.

That which is claimed is:
 1. A method of emplacing a catheter into apatient where the route of advancement of said catheter into the patientis defined by a guidewire having a segment protruding from the patient,said guidewire segment being shorter than the catheter, which methodcomprises: advancing gripping tool means through the proximal end of alumen of said catheter while causing a laterally projecting handle ofsaid gripping tool means to project laterally outwardly through alongitudinally extending slit defined in said catheter; bringing theproximal end of said guidewire and said gripping tool into engagementwhereby said guidewire proximal end is gripped by the tool; and graspingthe laterally outwardly projecting handle of said tool while advancingsaid catheter around and along said guidewire into the patient towardsaid implanted catheter site, to prevent advancement of said guidewire,said tool sliding relatively proximally along the slit of said catheteras the catheter is advanced.
 2. The method of claim 1 in which saidcatheter defines a proximal hub defining a conduit communicating withsaid catheter lumen, and a longitudinal slot extending the length ofsaid hub between the conduit and the exterior, said slot being incommunication with said longitudinal slit of the catheter, and includingthe step of passing the laterally projecting handle through saidlongitudinal slot prior to engaging said longitudinally extending slit.3. The method of withdrawing a catheter from a patient in which thecatheter defines a lumen through which a guidewire extends, saidguidewire having a segment protruding from the patient, said guidewiresegment being shorter than the total catheter length, which methodcomprises: attaching gripping tool means to the proximal end of theguidewire; grasping a laterally outwardly projecting handle of saidgripping tool means while withdrawing said catheter along saidguidewire, and while causing the gripping tool means to slide within thelumen of said catheter and causing said laterally projecting handle ofsaid gripping tool means to project laterally outwardly through alongitudinally extending slit defined in said catheter to preventwithdrawal of said guidewire along with the catheter, said tool slidingrelatively distally along the slit of said catheter as the catheter iswithdrawn.
 4. The method of claim 3 in which said catheter defines aproximal hub defining a conduit communicating with said catheter lumen,and a longitudinal slot extending the length of said hub between theconduit and the exterior, said slot being in communication with thelongitudinal slit of the catheter, and including the step of passing thelaterally projecting handle through said longitudinal slot to engagesaid slit.
 5. A method of removing a catheter implanted in a patientwith a guidewire occupying a lumen of said catheter, the proximal endsof both said catheter and guidewire projecting outwardly from saidpatient, which method comprises: bending at least one of proximalportions of said guidewire and said catheter in a lateral direction todraw a portion of said guidewire outwardly through a longitudinal slitdefined in said catheter; and withdrawing said catheter from the patientwhile holding said guidewire adjacent to said longitudinal slit, to holdsaid guidewire stationary and to cause said catheter and slit to moveproximally relative to said guidewire, whereby said catheter may beremoved from the patient while the guidewire remains stationary.
 6. Themethod of claim 5 in which said catheter defines a proximal hub defininga conduit communicating with said catheter lumen, and a longitudinalslot extending the length of said hub between the conduit and theexterior, said slot being in communication with said longitudinal slitof the catheter, and including the step of passing a laterallyprojecting guidewire portion through said longitudinal slot prior topassing said portion through said longitudinal slit.